Pneumatic trigger



Mar n-1.1910 R. H. BELLM'AN Em 3,500,845

PNEUMATIC TRIGGER Filed July 27, 1966 2 Sheets-Sheet 1 IO v I -12 I l I.ll l lfl lll Fig. I

INVENTORS. Robert H Bel/man F 2 BY Thomas W Berme/ 44%, 57%- A r TORNEXM h 17, 1970 R. H. BELLMAN ETAL 3,500,845

PNEUMATIC TRIGGER Filed July 27, 1966 2 Sheets-Sheet z INVENTORS.

Robert h. Bel/man BY Thomas W Berme/ M 5;, W ATTORNEY United StatesPatent 3,500,845 PNEUMATIC TRIGGER Robert H. Bellman and Thomas W.Bermel, Corning, N.Y., assignors to Corning Glass Works, Corning, N .Y.,a corporation of New York Filed July 27, 1966, Ser. No. 568,233 Int. Cl.F15c 1/04 U.S. Cl. 13781.5 5 Claims ABSTRACT OF THE DISCLOSURE A fluidoperated device for producing an output fluid stream in response to afluid control signal which has attained a predetermined minimumthreshold level. The device consists of at least one proportionalamplifier, the two outlet passages of which are connected to the controlpassages of a bistable fluid amplifier. A source of biasing fluid isconnected to one of the control orifices of the proportional fluidamplifier. The fluid control signal is connected to the opposing controlorifice and causes the bistable fluid amplifier to switch when thecontrol signal overcomes the bias.

This invention relates to fluid operated devices and more particularlyto an adjustable pneumatic switch or pneumatic trigger, but is notlimited to such applications.

Generally in a fluid amplifier, a high energy fluid stream, hereinafterreferred to as the power stream issues into an interaction chamber froma nozzle or orifice constructed such that the power stream is welldefined in space, which stream is directed toward a receiving apertureby the pressure distribution in the power stream.

boundary layer region. This pressure distribution is controlled by thewall configuration of the interaction chamber, the power stream energylevel, the fluid transport characteristics, the back loading of theamplifier outlet passages, and the flow of control fluid to the boundarylayer region.

In accordance with Bernoullis Theorem, the high velocity power streamissuing from the power stream orifice creates regions of low pressureadjacent the interaction chamber wall and this together with theconfiguration of the interaction chamber in part cause the power streamto lock-on to one sidewall and remain in the locked-on condition withoutany control fluid flow. Control fluid flow is brought about by controlfluid orifices which issue a control stream directed toward the powerstream in a direction generally perpendicular thereto. In a bistablefluid amplifier, the power stream can be deflected to the opposite wallof the interaction chamber by the control stream and be caused tolock-on thereto, as heretofore described, and remain there even afterthe control stream has been terminated. In a monostable fluid amplifier,the power stream can lock-on to one wall only. It

can be deflected to the opposite wall but only for such time as there isa control stream and when the control stream has been terminated thepower stream will automatically return and lock-on to the first wall.

The apparatus is provided with two outlets or fluid recovery aperturesor passages facing the power stream, which outlet passages are arrangedsuch that when the power stream is locked-on to one wall in either abistable or monostable device, substantially all the fluid of the powerstream is directed to one of the outlet passages and when it islocked-on or deflected to the other wall, as in bistable and monostabledevices respectively, substantially all the fluid of the power stream isdirected to the other of the outlet passages. The fluid so directed toeither or both of the passages may be delivered to utilization devicesas desired.

A low energy stream can deflect the well defined high energy powerstream to the extent required to cause a substantial portion of thestream to be delivered to one of the outlet passages while the integrityor the well defined character of the power stream is retainedsufliciently after interaction of the two streams so that the totalenergy or change in total energy delivered to such outlet passage can begreater than the energy or change in energy required to accomplish thisdeflection.

In an ordinary monostable fluid amplifier, where the power stream isstable when flowing through one outlet passage but must be continuouslydeflected to flow in the other outlet passage, the duration of the flowin the power stream outlet passage toward which it must be deflected,that is in which condition it is unstable, is directly proportional tothe duration of the control fluid flow.

It is an object of this invention to provide a fluid device which canproduce a digital output from an analog input.

Another object of this invention is to provide an economic pneumaticswitch having low hysteresis, high frequency, and adjustable triggerpoint where the input signal is independent of the output loading.

A further object of this invention is to provide an adjustable pneumaticswitch which operates predictably.

Broadly, according to the present invention a fluid device is providedhaving a bistable fluid amplifier of the type having interconnectedfluid passages whereby a well defined power stream may flow from a meansfor issuing said power stream to one of two outlet passages, and acontrol means for alternately switching the power stream from One of theoutlet passages to the other of the outlet passages. The device also hasa means for issuing a second stream of fluid under pressure and has apair of control passages one end of each of which is connected to thecontrol means of the bistable fluid amplifier while the other ends ofthe control passages are positioned in a spaced and stream interceptingrelationship with the means for issuing the second stream. Also providedis a means for controlling the amount of fluid of the second streamflowing in each of the control passages such that the bistable fluidamplifier power stream can be caused to switch from one of the outletpassages to the other. The invention also embodies means for amplifyingthe second stream of fluid as well as the output from the bistable fluidamplifier.

Additional objects, features, and advantages of the present inventionwill become apparent to those skilled in the art from the followingdescription and the drawings on which, by way of example, only thepreferred embodiments of this invention are illustrated.

FIGURE 1 is a side elevation of a fluid operated device embodying thepresent invention.

FIGURE 2 is a plan view of a fluid operated device embodying the presentinvention.

FIGURE 3 is a pneumatic schematic diagram of the device of FIGURE 2.

FIGURE 4 is a pneumatic schematic diagram of another embodiment of thepresent invention.

The stream fluid may be compressible such as air nitrogen, or othergases, or incompressible such as water or other liquids. Both thecompressible or incompressible fluids may contain solid material. Thisinvention is not limited to any particular fluid.

Referring to FIGURE 1, a fluid operated device is illus-' tratedcomprising plates 12, 14, and 16 within which suitable passages orapertures are formed. The passages and internal apertures in plates 12and 16 must be formed to a depth less than the plate thickness sincethese plates are also covers for the device. For example, the device maybe formed partly in one of the plates while the balance of it beingformed in another of the plates with the plates thereafter beingassembled in such a manner as to permit proper interconnection of thepassages. Tubes 18, 20, and 22 provide suitable connection to thevarious passages. Plates 12, 14, and 16 are shown bonded together byfusion. For ease of description and illustration, plate 12 is formed oftransparent material.

Plates 12, 14, and 16 may be formed of any suitable material such asmetal, glass, ceramic, plastic, or the like, and may be secured, sealed,or bonded together by any suitable method well known to one familiarwith the art, such as fusion of the plates together, securing the plateswith screws, and the like.

Referring to FIGURES 2 and 3, a suitable source of high pressure fluid,not shown, is connected to aperture 24 from which the fluid flowsthrough power stream orifice 26 and emerges therefrom as a well definedhigh energy power stream which enters interaction chamber 28 and passesto either of two outlet passages 30 and 32. Control fluid orifices 34and 36 are provided at the interaction chamber. The walls of theinteraction chamber of a bistable fluid amplifier are formed, in amanner well known to one familiar with the art, so that the power streamis caused to lock-on to one sidewall and remain in the locked-oncondition without any control fluid flow. The power stream can bedeflected to the opposite wall of the interaction chamber by controlfluid flow and remain locked-on even after the control fluid flow hasbeen stopped. Vent orifices 38 permit entrainment flow for the powerstream in a manner well known to one familiar with the art. Outletpassages 30 and 32 may be connected to suitable utilization devices, notshown, such as that hereinafter described.

A second suitable source of high pressure fluid, also not shown, isconnected to aperture 40 from which the fluid flows through streamorifice 42 and emerges therefrom as a well defined stream. A pair ofcontrol passages 44 and 46, one end of which passages is connected tocontrol fluid orifices 34 and 36 respectively, have the other endsthereof positioned in a spaced and stream intercepting relationship withorifice 42. Chamber 48 separates orifice 42 and the inlet to controlpassages 44 and 46, which chamber is constructed such that no sidewallsare present onto which the stream issuing from orifice 42 can lockon.Chamber 48 is directly connected to vents 50.

A suitable source of bias fluid is connected to aperture 52 from whichit flows through orifice 54 into chamber 48. A suitable source of fluidcontrol signals is connected to aperture 56 from which they flow throughaperture 58 into chamber 48.

The method of operation of such a pneumatic switch is as follows. When asource of high pressure fluid is connected to aperture 24, the welldefined high energy power stream emerging from orifice 26 initiallylocks-on to either wall 64 of outlet passage 30 or wall 66 of outletpassage 32. For this description, it is assumed that the power streamwill initially lock on to wall 64 causing the power stream to flowthrough outlet passage 30. Another source of fluid under pressure isconnected to aperture 40 with a stream emerging from orifice 42. Sincethere are no sidewalls onto which stream 42 may lockon, it will entercontrol passages 44 and 46 in proportion to the bias and control signalfluid flows as hereinafter described. A source of bias fluid at apredetermined pressure is connected to aperture 52 and emerges fromorifice 54 to impinge upon the stream emitting from orifice 42. Thepressure and flow of the biasing fluid is predetermined and controlled,as for example by a valve, such that the stream emerging from orifice 42will be deflected into passage 44. A source of fluid control signals isconnected to aperture 56 and a control signal fluid flow will emergefrom orifice 58 and also impinge on the stream emerging from orifice 42.Ordinarily orifices 54 and 58 are formed to the same size, whereupon,the stream emitting from orifice 42 will tend to enter control passages.4 44 and 46 in proportion to the pressure of the fluid emerging fromorifices 54 and 58. For example, when there is no flow through orifice58 the stream emerging from orifice 42 will be deflected by the biasfluid and will enter passage 44. As fluid flows through orifice 58 andimpinges on the stream emerging from orifice 42 it will tend to deflectit toward passage 46 and the stream will be divided between passages 44and 46. When the flow through orifice 58 has increased to a point suchthat it completely overcomes the bias flow from orifice 54, the streamemerging from orifice 42 will be completely deflected into passage 46.It is seen that depending on the fluid flowing through orifices 54 and58, the stream emerging from orifice 42 may be proportioned betweenpassages 44 and 46 and such a device is termed a proportional fluidamplifier. A proportional fluid amplifier may also be constructed with avent passage disposed intermediate control passages 44 and 46 so thatthe stream emitting from orifice 42 may be exhausted when the controlsignals and bias fluid are about equal.

When a bias fluid flows through orifice 54 sufficient to deflect asubstantial portion of the stream emerging from orifice 42 into passage44 most of it will emerge from control orifice 34 causing the powerstream which has been locked-on to wall 64 to be deflected to outletpassage 32 whereupon it will become locked-on to wall 66. When a fluidsignal is applied to aperture 56 suflicient to overcome the flow fromorifice 54 and to further deflect the stream emerging from orifice 42into control passage 46, most of the stream will be emitted throughcontrol orifice 36 and cause the power stream emitting from orifice 26to be deflected from outlet passage 32 to outlet passage 30 and becomelocked-on to wall 64.

It is, therefore, seen that depending on the flow of control signalfluid and the setting of the bias pressure and flow, an output may bealternately received from passages 30 and 32. The outlet of passage 30or 32 may be connected to an alarm, counter, indicating device, or thelike. The source of signals connected to aperture 56 may be a liquidlevel control, or a indicator producing a signal when a machine tooltraverses a predetermined distance, or the like. If, for example,aperture 56 were connected to a source of fluid signals emanating from aliquid level controller sensing a liquid level in a tank, and outletpassage 30' were connected to a means for introducing liquid into thetank, the pneumatic switch could be employed to maintain the levelwithin the tank by energizing the means for filling the tank each timethe liquid level dropped below a predetermined point.

Since the amount of biasing fluid may be regulated and controlled, thetriggering point at which the power stream emerging from orifice 26 maybe deflected can be controlled.

Referring now to FIGURE 4, another embodiment of the present inventionis shown. Three proportional fluid amplifiers 68, 70, and 72 areconnected in series such that the output of each amplifier is connectedso as to become the control fluid for the next succeeding amplifier.-Accordingly, the output of amplifier 68 passes through control passages74 and 76 and is emitted from control orifices 78 and 80 of amplifier 70and becomes the control fluid for amplifier 70. Similarly the outputfrom amplifier 70 passes through control passages 82 and 84 and isemitted from control orifices 86 and 88 of amplifier 72 and becomes thecontrol fluid for this amplifier. The output of amplifier 72 passesthrough control passages 90 and 92 and is emitted from control orifices94 and 96 of bistable fluid amplifier 98 thereby becoming the controlfluid for amplifier 98. Outlet passage 100 of bistable fluid amplifier98 is connected to control orifice 102 of OR-- NOR gate 104. The otheroutput passage 106 of amplifier 98 is vented to ambient. OR-NOR gate 104is a monostable device which is stable when the output is flowingthrough outlet passage 108 thereof. The output of gate 104 can bedeflected to outlet passage 110 only by providing a fluid flow throughcontrol orifice 102.

Control orifice 112 of amplifier 68 is connected to a suitable source offluid control signals, while control orifice 114 is connected to asource of biasing fluid which is regulated and controlled by some means,such as valve 116, before emitting from control orifice 114. Inletapertures 118, 120, 122, and 124 of amplifier 68, 70, 72, and 98respectively are shown connected in common, to which common connection asuitable source of high pressure fluid, not shown, is connected. Theseinlet apertures could be connected to individual sources of highpressure fluid if such is desired. Inlet aperture 126 of gate 104 isshown provided with a separate connection to a suitable source of highpressure fluid.

The advantages of the embodiment shown in FIGURE 4 are that a smalldifferential between the bias fluid and the control signal can be usedto deflect the output from outlet passage 106 to outlet passage 100 ofamplifier 98 by amplifying this difference through a plurality of stagessuch as for example amplifiers 68, 70, and 72. Thus a minute diflerencemay be amplified to be suflicient to operate amplifier 98. The advantageof employing gate 104 is that the output from this gate will flow in oneoutlet passage only unless and until the control signal emitting fromcontrol orifice 112 is of suflicient magnitude so as to overcome thebias fluid by a predetermined amount at which time the output from gate104 will be caused to be emitted from outlet passage 110. As soon as thecontrol signal falls below the predetermined level, the output from gate104 will return and flow through outlet passage 108. Another advantageof employing gate 104 is that the output signal therefrom may have ahigher pressure by connecting a separate source of high pressure fluidto inlet aperture 126.

One familiar with the art will readily understand that the final designparameters of specific fluid devices will at least depend upon the fluiddensity, temperature, and pressure as well as the characteristicsrequired of the output stream at the point of utilization.

Although the present invention is described with respect to specificdetails of certain embodiments thereof, it is not intended that suchdetails be limitations upon the scope of the invention except insofar asset forth in the following claims.

We claim:

1. A phenumatic switch comprising a bistable fluid amplifier of the typehaving interconnected fluid passages whereby a well definedsubstantially continuous power stream may flow from a means for issuingsaid power stream to one of two outlet passages,

control means for alternately switching said power stream from one ofsaid outlet passages to the other of said outlet passages,

utilization means connected to said outlet passages,

an orifice for issuing a stream of fluid under pressure,

a pair of control passages having one end each connected to said controlmeans and the other ends thereof being positioned in a spaced and streamintercepting relationship with said orifice for issuing a stream,

a chamber intermediate said orifice for issuing a stream and saidcontrol passages having a configuration such that said stream of fluidwill not lock-on to either sidewall,

a pair of control orifices communicating with said chamber,

a source of fluid signals connected to one of said control orificesonly,

a source of biasing fluid connected to the other of said controlorifices, and

means for regulating the pressure of said biasing fluid,

said stream of fluid being apportioned between said control passages inresponse to said fluid signals and said biasing fluid, the portion ofsaid stream of fluid entering each of said control passages beingsubstantially wholly transmitted to said control means.

2. A pneumatic switch comprising a proportional fluid amplifier of thetype having interconnected fluid passages whereby a stream of fluid mayflow from a means for issuing such a stream to a plurality of outletpassages, first orifice means for directing a stream of biasing fluidagainst said stream of fluid, and second orifice means opposed to saidfirst orifice means for directing a stream of fluid signals against saidstream of fluid, thereby controlling the amount of said stream of fluidflowing in each of said outlet passages,

said proportional fluid amplifier having a chamber intermediate saidmeans for issuing said stream of fluid and said outlet passages having aconfiguration such that said stream of fluid will not lock-on to eithersidewall, means for controlling the pressure of said biasing fluid, abistable fluid amplifier of the type having interconnected fluidpassages whereby a well defined power stream may flow from a means forissuing said power stream to one of two outlet passages,

utilization means connected to said bistable fluid amplifier outletpassages,

control means for alternately switching said power stream from one ofsaid outlet passages of said bistable fluid amplifier to the other ofsaid outlet passages, and

a pair of control passages communicating between said outlet passages ofsaid proportional fluid amplifier and the control means of said bistablefluid amplifier, the portion of said stream of fluid entering each ofsaid control passages being substantially wholly transmitted to saidcontrol means.

3. The pneumatic switch of claim 2 further comprising an OR-NOR gatehaving a pair of outlet passages, the control orifice of which isconnected to one of said outlet passages of said bistable fluidamplifier, said utilization device being connected to the outletpassages of said ORNOR gate.

4. A pneumatic switch comprising a plurality of proportional fluidamplifiers of the type having interconnected fluid passages whereby astream of fluid may flow from a means for issuing such a stream to aplurality of outlet passages in response to means for controlling theamount of said stream of fluid flowing in each of said outlet passages,

said proportional amplifiers being connected such that the flow throughthe outlet passages of each amplifier being the control fluid for saidmeans for controlling of the next successive amplifier, the means forcontrolling of the first of said proportional amplifiers being a pair ofopposing control orifices one of which is connected to a source of fluidsignals while the other is connected to a source of biasing fluid,

a bistable fluid amplifier of the type having interconnected fluidpassages whereby a well defined power stream may flow from a means forissuing said power stream to one of two outlet passages,

control means for alternately switching said power stream from one ofsaid outlet passages of said bistable fluid amplifier to the other ofsaid outlet passages,

a pair of control passages communicating between the outlet passages ofthe last of said proportional amplifiers and the control means of saidbistable fluid amplifier, and

a monostable fluid amplifier, the control orifice of which is connectedto one of said outlet passages of said bistable fluid amplifier.

7 8 5. The pneumatic switch of claim 4 further compris- 3,223,10112/1965 Bowles 137-815 ing a means for controlling the pressure of saidbiasing 3, 1/1966 Warren t a 13781.5 fl id, 3,240,220 3/1966 Jones137-815 References Cited 3,277,914 10/1966 MBlliOIl 137-81.5 3,340,8859/1967 Bauer 137-815 UNITED STATES PATENTS SAMUEL SCOTT, PrimaryExaminer 3,443,573 5/1969 Posingies 137 s1.5 3,443,574 5/1969 Posingies137-s1.5 Us. 01. X.R. 3,107,850 10/1963 Warren et a1. 137 s1.5 XR 2352013,155,825 11/1964 Boothe 13781.5 XR 10

